Astyanax is a side-scrolling platform game. The game also contains a few role-playing elements, such as weapons upgrades. It had a unique feature (for the time) of a bar that grows between attacks; the length of the bar determines how much damage Astyanax will do with his next attack.

Cheats:
Unlock the Demo Select menu, then press B, B, A, A, B, A, Up, Down, Start to see the ending sequence. Oddly enough, this ending is different from the usual one in that it shows the developer credits at the end.
Continue A, B, Select, Start (when you get game over)
Demo Select Up, Up, Up, Down, Down, Down, A, B, Start
Invincibility Up (4x), Down, Left, Right, Up, Start (on title screen)
Level Select Up, Down, Left, Right, B (4x), Start (on title screen)
Sound Test Up, Down, Right, Left, Up, Down, Right, Left, Start
View Ending & Credits B, B, A, A, B, A, Up, Down, Start (on Demo Select menu)